This invention relates to a latent image formation object for preventing valuable printed matter such as bills (paper money), bank notes, security papers, credit cards, passports, etc. from being counterfeited or falsified, and a method for making the same.
In general, valuable printed matter such as bills, security papers, credit cards, passports, etc. are required to include safeguards such that they are very difficult to be counterfeited or falsified. In order to meet with this requirement, many attempts have heretofore been made. In a typical technique, a watermark is formed in such sheets of paper. In another attempt, a distinctive substance (security thread, colored fiber, etc.) is inserted into such sheets of paper. There is also a technique in which such sheets of paper are provided with many projections and recesses (irregularities) on surfaces thereof.
However, the watermarked sheets of paper have such shortcomings that it is difficult to visually recognize the watermarked pattern unless the sheets of paper are looked through carefully. Moreover, it is possible to imitate the watermark by the printing using varnish, etc. Therefore, this watermark technique is not presently a perfect anti-counterfeit means.